Modes | Engineering Notes India

Convection: Meaning and Properties | Thermal Engineering

In this article we will discuss about:- 1. Meaning of Convection 2. Laminar and Turbulent Flow of Fluid Affecting Convection 3. Newton-Rikhman Law 4. Dimensionless Group 5. Significance. Contents: Meaning of Convection Laminar and Turbulent Flow of Fluid Affecting Convection Newton-Rikhman Law: Convection Rate Equation Dimensionless Group for Convection Significance of Dimensionless Groups for Convection 1. Meaning of Convection: Thermal [...]

By Jayanta S|2017-12-07T08:56:01+05:30December 7, 2017|Convection|Comments Off

Conduction with Heat Generation | Thermal Engineering

In many situations of practical importance, heat is generated internally at uniform rate within the conducting medium itself. Notable examples are: (i) Resistance heating in electrical appliances; essentially it is the conversion of electrical energy into thermal energy in the current carrying medium (ii) Energy generated in the fuel element of a nuclear reactor (iii) Liberation of energy due to [...]

By Jayanta S|2017-12-07T08:56:00+05:30December 7, 2017|Heat Conduction|Comments Off

Fick’s Law of Diffusion | Modes | Mass Transfer | Physics

In this article we will discuss about the Fick’s law of diffusion. Consider a chamber in which two different gas species, B and C, at the same temperature and pressure are initially separated by a partition. The left compartment has a high concentration of gas B (dark circles) whereas the right compartment is rich in gas C (white circles). Higher [...]

By Jayanta S|2017-12-07T08:55:58+05:30December 7, 2017|Diffusion|Comments Off

Diffusion of Water Vapours through Air | Mass Transfer | Physics

Consider evaporation of water contained in a tube or tank and its subsequent diffusion through the stagnant layer of air over it. Assumptions: (i) The system is under steady state and isothermal conditions (ii) The total pressure within the tube is constant and equal to the outside pressure (iii) Both air and water vapours behave as perfect gases (iv) Air [...]

By Jayanta S|2017-12-07T08:55:58+05:30December 7, 2017|Diffusion|Comments Off

Process of Diffusion for Mass Transfer | Physics

In this article we will discuss about the general equation for mass transfer. Also learn about equimolal diffusion. General Equation of Mass Diffusion: Consider mass balance of species B diffusing through a control volume (dx × dy × dz) in a solid or stationary fluid medium C. Accumulation of mass of species B in the elemental volume due to its [...]

By Jayanta S|2017-12-07T08:55:58+05:30December 7, 2017|Diffusion|Comments Off

Use of Radiation Shields to Reduce Heat Transfer | Thermal Engineering

Many situations are encountered where it is desired to reduce the overall heat transfer between two radiating surfaces. The task is accomplished by placing radiation shields between the emitting surfaces. The shields are thin opaque partitions arranged in the direction perpendicular to the propagation of radiated heat, and made of materials of very low absorptivity and high reflectivity (thin sheets [...]

By Jayanta S|2017-12-07T08:55:58+05:30December 7, 2017|Heat Transfer|Comments Off

Critical Thickness of Insulation | Thermal Engineering

Contrary to the common belief that addition of insulating material on a surface always brings about a decrease in the heat transfer rate, there are instances when the addition of insulation to the outside surfaces of cylindrical or spherical walls (geometries which have non-constant cross-sectional areas) does not reduce the heat loss. In fact, under certain circumstances, it actually increases [...]

By Jayanta S|2017-12-07T08:55:57+05:30December 7, 2017|Insulation|Comments Off

Process of Diffusion for Mass Transfer | Physics

In this article we will discuss about the general equation for mass transfer. Also learn about equimolal diffusion. General Equation of Mass Diffusion: Consider mass balance of species B diffusing through a control volume (dx × dy × dz) in a solid or stationary fluid medium C. Accumulation of mass of species B in the elemental volume due to its [...]

By Jayanta S|2017-12-07T08:55:57+05:30December 7, 2017|Diffusion|Comments Off

Coefficient of Radiant Heat Transfer | Thermal Engineering

The radiative heat exchange between two systems (surfaces) is generally calculated from the simplified equation- The factor hr is called the coefficient of radiant heat transfer from solid to solid and is expressed in W/m2-deg temperature difference between the enclosed and enclosing surfaces. The value of hr can be calculated from the heat flux equation for any configuration. For example, [...]

By Jayanta S|2017-12-07T08:55:57+05:30December 7, 2017|Heat Transfer|Comments Off

Free and Forced Convection (Correlations) | Thermal Engineering

In this article we will discuss about the empirical correlations for free and forced convection. Bulk Temperature and Mean Film Temperature: The physical properties (µ, k, ρ, cp) of a fluid are temperature dependent. Undoubtedly the accuracy of the results obtained by using theoretical relations and the dimensionless empirical correlations would depend upon the temperature chosen for the evaluation of [...]

By Jayanta S|2017-12-07T08:55:55+05:30December 7, 2017|Convection|Comments Off

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